102 Commercial Gardening 



less according to the nature of the soil. From 1 to 1| ac. can be ploughed 

 in a day, and it is this facility for turning over the ground quickly that 

 has made ploughing more popular than spade cultivation. When the 

 ground is "subsoiled" a subsoil plough follows the other in the trench 

 and moves the lower soil to a depth of 15 to 18 in. The cost of subsoiling 

 1 ac. of land would be about the same as for ploughing, thus making the 

 total cost per acre for the two operations from 80s. to 40s. There are 

 many kinds of ploughs now in use, but all have the same object in view, 

 namely, to turn the soil up as well and as quickly as possible at the least 

 expense. 



One of the latest inventions is an electric plough, invented by Mr. E. O. 

 Walker of Manchester. This is intended to supersede the steam plough, 

 wherever electric power can be procured easily and cheaply. Electric 

 wires overhead are used for a trolley as in tramcars, and the plough is 

 hauled across the field from one side to another as in the case of steam 

 ploughs. The same principles of shallow ploughing are adopted, but if 



Fig. 85. iHagram showing Water (W) standing between Ridges in Land ploughed 6 in. deep 



electricity or steam could be harnessed in such a way as to turn the soil 

 over to a depth of two or three feet, it would make a vast difference to the 

 fertility of the soil in the course of a year or two. 



The great disadvantage of ploughing is that the soil is not turned over 

 to a great depth, and a hard pan is formed beneath the loosened layer. In 

 some soils this pan is so hard that it is impossible for air or rain to enter 

 the subsoil; and it is just as difficult, for the same reason, for the tender 

 rootlets of the plant to extend their search for food. All the fertilizing 

 advantages to be derived from the drying and warming action of the air, 

 the solvent effects of the rain, and the penetrating power of the roots are 

 thus rendered abortive, or at least greatly reduced. The diagram (fig. 85) 

 shows how the water after a heavy rain remains on the surface between 

 the ridges in ploughed land, until it is evaporated by the heat of the atmos- 

 phere and the wind. Under such circumstances the soil is cold and wet, 

 and cannot be worked, while the beneficial bacteria cannot come into 

 being in the soil until warmer and drier conditions prevail. The hard 

 pan brought about by repeated ploughings has been recognized as such an 

 evil by some American farmers, that they have taken the heroic measure 

 of breaking the subsoil up by charges of dynamite. 



Digging. This operation is done with the spade or the fork. It is 

 a much better way of turning up the soil than with the plough. Not only 

 does the spade or fork go deeper, but the soil is turned over more com- 

 pletely, and the clods are broken down into much finer particles. An 

 expert workman will dig from 8 to 15 rods (about 240 to 450 sq. yd.) 



